This invention relates generally to the field of mounting brackets and in particular, to an apparatus and method for aligning a bracket member of a circuit board assembly as the bracket member is positioned against and secured to an electronic chassis.
An electronic chassis which houses electronic components for high speed telecommunication and networking applications typically includes a plurality of vertically oriented circuit board assemblies that are inserted into the chassis. Each circuit board assembly is typically comprised of a circuit board attached to a vertically oriented U-shaped channel member that serves as a front faceplate of the assembly. When the assembly is fully inserted, the circuit board is connected to a backplane printed circuit located along the backside of the chassis. The insertion force required to connect the circuit board to the backplane may make it difficult, if not impossible, for a technician to make the connection by manually forcing the channel member in a direction towards the backplane.
In order to facilitate the connection of the circuit board to the backplane, a lever having a handle portion and a hook portion is typically provided at each end of the channel member. Each lever is typically rotatably attached to each end of the channel member and is able to rotate about a pin that is attached to the channel member. When installing the circuit board assembly, a technician orients each hook portion to allow each hook portion to engage a flange portion of the chassis when the channel member is pushed in the direction of the backplane. After the hook portion engages the flange portion, the handle portion of each lever is then manually rotated about the pin, which forces the circuit board into the backplane.
Each channel member typically includes a gasket that is longitudinally oriented along the entire length of one of the sides of the channel member. When the circuit board assemblies are installed, the gasket of one channel member is positioned against one side of an adjacent channel member. The function of the gasket is to prevent electromagnetic emissions from exiting the chassis between two adjacent channel members. It is therefore critical that there be a proper amount of gasket compression along the entire length of the bracket member to ensure uniform electromagnetic interference shielding along the entire length of the bracket member. Moreover, since the plurality of circuit board assemblies in the chassis are in close proximity to one another, it is critical for each circuit board assembly to be properly aligned. This insures that the insertion force and the extraction force for each assembly is uniform so that the desired number of assemblies can be inserted into the chassis.
With conventional circuit board assemblies, the channel member is typically fastened to the chassis with conventional mechanical fastening components such as, for example, spring-loaded screws or bolts. The disadvantage of his arrangement is that each channel member must be aligned manually before the channel member is fastened to the chassis. However, it is extremely difficult to manually align each assembly to provide uniform gasket compression. Moreover, with mechanical fasteners, the tolerance between parts may result in the inconsistent placement of the channel members which may result in inconsistent gasket compression. This in turn may allow unacceptable levels of electromagnetic emissions to exit the chassis.
Accordingly, it would be desirable to have an apparatus for aligning a circuit board assembly to an electronic chassis that overcomes the disadvantages described above.
One aspect of the invention provides an apparatus for aligning a bracket member of a circuit board assembly as the bracket member is positioned against and secured to an electronic chassis. A circuit board assembly includes a circuit board operatively attached to a bracket member. The bracket member includes a first end, a second end, an outer surface, and an inner surface. A gasket is longitudinally oriented along the outer surface of the bracket member. A first pin extends from the inner surface adjacent the first end, and a second pin extends from the inner surface adjacent the second end. An electronic chassis includes a top flange and a bottom flange. The top flange includes a top flange opening, and the bottom flange includes a bottom flange opening. The first pin is aligned with and extends through the top flange opening and the second pin is aligned with and extends through the bottom flange opening to align the bracket member as the bracket member is positioned against and secured to the electronic chassis. The bracket member may preferably be a U-shaped channel member. The first and second pins each may preferably include a tapered end portion. Each of the first and second pins may preferably be approximately 0.125 inches in diameter and 0.400 inches in length. The gasket may preferably be comprised of a metallic material that prohibits the transmission of electromagnetic emissions. The top flange opening may preferably be a slot. The bottom flange opening may also preferably be a slot.
Another aspect of the invention provides an apparatus for providing uniform electromagnetic interference shielding between two adjacent circuit board assemblies. A first circuit board assembly includes a first circuit board operatively attached to a first bracket member. The first bracket member includes a first end, a second end, an outer surface and an inner surface. The first bracket member includes an electromagnetic interference gasket longitudinally oriented along a length of the outer surface. A first pin extends from the inner portion adjacent the first end, and a second pin extends from the inner portion adjacent the second end. A second circuit board assembly includes a second circuit board operatively attached to a second bracket member. The second bracket member includes a first end, a second end, an outer surface and an inner surface. The second bracket member includes an electromagnetic interference gasket longitudinally oriented along a length of the outer surface. A first pin extends from the inner portion adjacent the first end, and a second pin extends from the inner portion adjacent the second end. An electronic chassis includes a top flange and a bottom flange. The top flange includes a top flange opening and a second top flange opening, the bottom flange including a bottom flange opening and a second bottom flange opening. The electromagnetic interference gasket of the first bracket member is positioned against the outer surface of the second bracket member. The first pin of the first bracket member is aligned with and extends through the top flange opening and the second pin of the first bracket member is aligned with and extends through the bottom flange opening. The first pin of the second bracket member is aligned with and extends through the second top flange opening. The second pin of the second bracket member is aligned with and extends through the second bottom flange opening to evenly compress the electromagnetic interference gasket of the first bracket member with the second bracket member and provide uniform electromagnetic interference shielding along the length of the first and second bracket members.
Another aspect of the invention provides a method for aligning a bracket member of a circuit board assembly as the bracket member is positioned against and secured to an electronic chassis. A circuit board assembly including a circuit board operatively attached to a bracket member is provided. The bracket member includes a first end, a second end, an outer surface, and an inner surface. A gasket is longitudinally oriented along the outer surface of the bracket member. A first pin extends from the inner surface adjacent the first end, and a second pin extends from the inner surface adjacent the second end. An electronic chassis includes a top flange and a bottom flange. The top flange includes a top flange opening and the bottom flange including a bottom flange opening. The first pin is aligned with the top flange opening and the second pin is aligned with the bottom flange opening. The first pin extends through the top flange opening and the second pin extends through the bottom flange opening. The bracket member is aligned as the bracket member is positioned against and secured to the electronic chassis.
Another aspect of the invention provides a method for providing uniform electromagnetic interference shielding between two adjacent circuit board assemblies. A first circuit board assembly including a first circuit board operatively attached to a first bracket member is provided. The first bracket member includes a first end, a second end, an outer surface and an inner surface. The first bracket member includes an electromagnetic interference gasket longitudinally oriented along a length of the outer surface. A first pin extends from the inner portion adjacent the first end and a second pin extends from the inner portion adjacent the second end. A second circuit board assembly includes a second board operatively attached to a second bracket member. The second bracket member including a first end, a second end, an outer surface and an inner surface. The second bracket member includes an electromagnetic interference gasket longitudinally oriented along a length of the outer surface. A first pin extends from the inner portion adjacent the first end, and a second pin extends from the inner portion adjacent the second end. An electronic chassis includes a top flange and a bottom flange. The top flange includes a top flange opening and a second top flange opening. The bottom flange includes a bottom flange opening and a second bottom flange opening. The electromagnetic interference gasket of the first bracket member is contacted with the outer surface of the second bracket member. The first pin of the first bracket member is aligned with the top flange opening and the second pin of the first bracket is aligned with the bottom flange opening. The first pin of first bracket extends through the top flange opening and the second pin of the first bracket member extends through the bottom flange opening. The first pin of the second bracket member is aligned with the second top flange opening and the second pin of the second bracket is aligned with the second bottom flange opening. The first pin of second bracket extends through the second flange opening and the second pin of the second bracket member extends through the second bottom flange. The electromagnetic interference gasket of the first bracket member is compressed with the outer surface of the second bracket member. Uniform electromagnetic interference shielding is provided along the length of the first and second bracket members.
The invention provides the foregoing and other features, and the advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention and do not limit the scope of the invention, which is defined by the appended claims and equivalents thereof.